Drafting instrument.



J. H. EWBANK. DRAFTING INSTRUMENT.

APYLIOATION FILED MAY 13, 191B.

Patented ct.7 ,11913.

J. H. EWBANK.

DRAPTING INSTRUMENT. APPLICATION FILED MAY 13. 1912.

lmwmn Patented @013. 119113.

2 SHEETB-BKEET 2.

James H. nwsnnx, or newnnncnnnne, more.

nnnrrme INSTRUMENT.

not/asst. I

' Specification of Letters Patent.

Patented eat. a, rare.

Application filed May 13, 1912. Serial No. 697,018.

To all whom it may concern:

Be it known that L-J-AMns H. EWBANK, citizen of the United States, residing at Lawrenceburg, in the county of Dearborn and State of Indiana, have invented certain new and useful Improvements in Drafting Instruments, of which the following is a specification.

My invention relates to new and useful improvements in drafting instruments and more particularly to that type of drafting instrument employed in platting surveys and the like, and the object of my invention is to provide an instrument including a drawing board or table and a rule adjustable to any angle and movement to any part of the board or table.

A further object of my invention is to provide a support having tracks, and an instrument movable upon the tracks and including a meridian bar extending transversely between the tracks, and a rule bearing carriage mounted for movement upon the meridian bar.

A further object of my invention is to provide means for adjusting the rule angularly with respect to its carriage and, for locln'ng the rule in adjusted angular position. A further object of my invention is to provide means for locking the meridian bar against movement on its track and the carriage against movement on the meridian bar.

A further object of my invention is to provide means independent of the primary angular adjusting means of the rule for setting the device for any variation of the compass from the true meridian. And a still further object of my invention is to provide an instrument particularly adapted for copying plats and which may be employed in making an enlarged ora reduced copy and making the same to scales.

"With these and other objects in view, my invention will be more fully described, illustrated in the accompanying drawings, and then specifically pointed out in the claims which are attached to and form a part of this application.

In the drawings: Figure 1 is a top plan view of-my instrument, showing the same in operation Fig. 2 is a section on the line 2-2 of Fig. 1; Fig. 3 is a section on the line 3-3 of Fig. 1; Fig. 4 is a fragmentary section on the line H of Fig. 2, showing the I form of lock employed in securing the carriage against movement on the meridian bar; Fig. 5 is a detail sectiontaken through the line 5-5 of Fig. 2, showing the construction of the double circle protractor supported by the carriage and bearing against the scale.

Corresponding and like parts are referred to in the following description and indicated in all the views of the drawings by the same reference characters.

The preferred embodiment of my invention includes a plane surfaced support 10 such as a table or drawin board provided at its edges with longitu inally extending tracks 11, the ends of which are secured to the board as shown at 12, while the remainder of the tracks are spaced above the board as shown at 13 to permit the positioning of the drawing pa er or cloth beneath the tracks when desire a partially finished drawing being represented conventionally at 14. Mounted for movement upon these tracks and consequently longitudinally of the support, is a meridian bar, designated as a whole b the numeral 15. This bar includes space end members 16 connected at their upper ends by parallel spaced rods 17 forming a track for the movable carriage, as will be hereinafter explained. The end members 16 are provided at their lower ends with supporting wheels 18 which bear upon the tracks 11, these wheels having track engaging flanges 19 which prevent their becoming disengaged from the track and which insure the maintaining of the meridian bar in absolute parallelism with the ends of the support in all positions.

As a means for locking the meridian bar in adjusted position upon its tracks, I have provided the inner faces of the end members 16 with vertically spaced apart, perforated ears 20 through which are slidably mounted spring pressed catches 21. Each of these catches includes a body member movable through the ears and terminating at its lower end in a laterally directed extension 22 which passes beneath the end members 16 and engages against the lower face of the adjacent track 11 and which terminates at its upper end in an oppositely directed arm 23 by means of which the catch may be moved downwardly to disengage it from the track. This catch is normally maintained in operative position by means of a helical spring 24 which surrounds the body member cluding 'albody-member 27 provided at itsends withwheels 28 adapted Ior' engagementwith the tracks 17. As a means for locking this carriage in adjusted position upon its tracks, I have provided pins 29 which are movable vertically through the central end portions of the carriage and which pass through locking bars 30, the ends of which extend oppositely beneath the tracks 17 and in vertical alinemcnt with the adjacent wheels 28 of the carriage. The upper ends of these pins 29 are headed as shown at 31 and surrounding each of these pins and bearing against the head and the carriage, are helical springs 32 which serve to normally maintain the bars in engagement with the tracks. The pins are preferably angular in section to prevent. their turning and therefore prevent the bars 30 from swinging out of position. As will be readily seen, a slight downward pressure upon the head 31 of the pins will more the bars 30 out of engagement with thetracks and permit the free movement of the carriage. Supported by this carriage and beneath the meridian bar, is a double circle protractor designated as a whole by the numeral 33 and including an outer protractor circle 34 and an inner protractor circle 35, both circles being properly scaled, as shown. The inner protractor circle is secured to the feet 36 of a plurality of legs 37 which-converge upwardly and inwardly to a cylindrical body member 38. This cylindrical body member is provided with a central bore keyedin which is a bolt 39, the free end of which passes through a suitable bore formed in the central portion of the carriage 25 and into a worm gear 40 which rests upon the upper face of the carriage.

The carriage is provided with upwardly directed, spaced apart, perforated ears 41 in which is journaled a worm threaded shaft 42, the thread of which meshes with the teeth of the gear 40. The free end of shaft 42 is provided with a milled head 43'by means of which the shaft may be turned to rotate the gear 40 and consequently turn the double circle protractor to various positions to adjust it for variations for surveys made by magnetic meridian. As a means for determining. the proper adjustment, I have provided a vernier 44, one member of which is mounted upon the carriage in such a manner as to extend by its scale edge over the gear 40 and the other member of WhJOh is mounted upon the gear with its other edge bearing against the scale edge of the first mentioned member.

The inner protractor circle has the outer portion of its upper face stepped to form concentric angular shoulders 45 and 46,

while the lower inner portion of the outer protractor circle is provided with a shoulder 47 which engages with the shoulder 45 to support the outer circle upon the inner circle. The upper face of the outer circle is the same time it is free to turn about the in-= ner protractor circle. As a means for locking the circles in adjusted relative position, I have provided a thumb screw 51 which is threaded through the ring 49 and which may be turned to engage against that portion of the outer circle formed by the shoulders 47 and 48 and thus clamp the circles together.

Previously, the inner circle and the ring 49 have been spoken of as a single element and designated by the numeral 33, and in general these two members are considered as a unit making up the inner protractor 'circle of the double circle protracton. The scale of the inner protractor circle, as shown in Fig. 1, has in fact been described upon the ring 49 rather than upon the inner protractor circle proper.-

The outer protractor circle 34 is provided at one side with an outwardly and downwardly directed extension 52 carrying at its free end a rule 53, the opposite edge portion of which may be scaled, as shown. This extension 52 is so proportioned as to maintain the rule 53 in slightly spaced position above the drawing board or support to per mit the free movement of the instrument over' thesame and is preferably formed of resilient metal so as to permit the depression of the rule in engagement with the paper, when desired.

From the foregoing description, the operation of the instrument will be readily understood. The paper or other material upon which theplator diagram is to be made is securely fastened to the board or table in the usual manner. The double circle protractor is then adjusted by means of the vernier 44 for any variation of the compass from the true meridian when the outer protractor circle is turned to the for the first course of the plat and locked in place. A certain point upon the paper is specific angle selected as the starting point and the plat 13o ,the. carriage,

or ma to be drawn and the meridian bar is move over the board and the carriage along the meridian bar until the rule has been brought to this point when a line f the proper length, is laid off from the point, the length being either determined by proportional dividers or by the scale upon the rule. The outer protractorcircle is then again adjusted at the proper angle for the next course which is laid off in the same manner, this operation being continued until the plat is complete.

It will be apparent that by providing means for moving the rule to all angles, the work is greatly simplified as the proper angle may be readily laid off upon the plat. By mounting the meridian bar for longitudinal movementupon the board and the carriage for longitudinal movement upon the meridian bar, the rule 1s so supported that it may be brought to any part of the board desired when adjusted at any angle. By providing means for locking the meridian bar, carriage and protractor circles in adjustedposition, I have insured absolute mechanical accuracy. One of the'chief advantages of my instrument and one which will be readily apparent is the ease with which a series of parallel lines may be laid ofi upon the work.

To permit absolute freedom of movement, when desired, I have supplied Z-shaped buttons Madjacent each each of the pins 29 which may be swung toengage the catches orpins as the case may be and hold them in depressed position. Having thus described the invention, what is claimed as new is:

1. A platting instrument including a support," a meridian bar movable over said support, a carriage movable on the meridian bar, a protractor supported by said carriage, and a rule tangential to and carried by said rotractor.

2. platting instrument including a support, a meridian bar movable over the support, a carriage movable upon the meridian bar, a double circle protractor supported by means for adjusting the protractor angularly with respect to the meridian bar, means for adjusting the protractor circles with respect to each other, and a rule rigidly secured to one of the protractor circles.

3. A platting instrument includin a support, tracks on the support, a meri an bar mounted for movement on the tracks, a cart'lage against of the catches 21 and riage mounted for movement on the bar, loc s for automatically locking the bar against movement on the tracks and the carmovement on the bar, and catches movable into engagement with the locks to hold the latter in inoperative position.

4. A platting instrument includin a support, tracks on the support, a meri ian bar mounted for movement on. the tracks, a carriage mounted for movement on the bar, locks for automatically holding the bar against movement on the tracks and the carriage against movement on the bar, each of said locks including a brake bar carried by the movable member and extending beneath the tracks, and a spring normally holding said brake bar in engagement with the tracks.

5. A platting instrument including a Support, a meridian bar mounted for movement over the support, a carriage movable along the meridian bar, and a double circle roso tractor supported by the carriage, one 0 the protractor circles being entirelyindependent of the carriage and adjustably mounted upon the other protractor circle.

6. A platting instrument including a support, a meridian bar mounted for movement over the support, a carria e movable along the meridian bar, and a ouble circle protractor supported by the carriage, one of the rotractor circles being entirely indepen ent of the carriage and adjustably mounted upon the other protractor circle, said independent protractor circle having an integrally formed extension providing a rule.

7 A platting instrument. including a support, a meridian bar movable over the support, a carriage movable on the meridian bar and provided centrally with an openin a bolt rotatable in said opening, a worm ear keyed upon the upper end of said bo t, a worm shaft coacting with said gear, a tubular body member keyed u on the opposite end of the bolt and provide with downwardly projecting diverging legs, and a protractor secured to said legs and supported beneath the carriage.

In testimon whereof I aflix my signature in .presence 0 two witnesses.

ISABEL Brogan, THUS. S, I H 

